The origin of high PCE in PTB7 based photovoltaics: proper charge neutrality level and free energy of charge separation at PTB7/PC71BM interface

• DOI: 10.1038/srep35262
• Publication Date: 2016-10-13T09:48:42Z
• Authors: Soohyung Park; Junkyeong Jeong; Gyeongho Hyun; Minju Kim; Hyunbok Lee; Yeonjin Yi
• Keywords: Neutrality; Interface (matter)

The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role device performance. However, little is known about the interfacial energetics polymer OPVs due to technical issues of solution process. Here, frontier ortbial line-ups interface high performance OPVs, PTB7/PC71BM, were investigated using situ UPS, XPS and IPES. evolution levels during PTB7/PC71BM formation was vacuum electrospray deposition, compared with that P3HT/PC61BM. At interface, dipole band bending absent their identical charge neutrality levels. In contrast, large observed P3HT/PC61BM interface. measured photovoltaic gap (EPVG) 1.10 eV for 0.90 This difference EPVG leads larger open-circuit voltage than